Computer Chess Club Archives




Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Uri Blass

Date: 00:29:51 07/21/02

Go up one level in this thread

On July 21, 2002 at 03:16:40, Sune Fischer wrote:

>On July 20, 2002 at 22:22:22, Robert Hyatt wrote:
>>On July 20, 2002 at 08:13:44, Gian-Carlo Pascutto wrote:
>>>On July 20, 2002 at 08:04:01, Sune Fischer wrote:
>>>>I think it matters "a factor of 2".
>>>>1) it helps you to prune
>>>>2) you get better evaluation in the upper plies when you can return a score
>>>>based on a deeper search.
>>>>number one will show itself directly because you iterate deeper, the second one
>>>>you don't "see", but it does improve depth along some branches in the same way.
>>>1) I get +- 10% hash hits (and less prunes) in typical middlegame. Not enough to
>>>matter a factor of two (but I didnt check this so not 100% sure).
>>>2) Uh?
>>Run your program with a tiny hash and a deep search.  Then a big hash and
>>a deep search.  In middlegame positions this will be at least a factor of
>>2x.  Measure time to depth.  Small hash might take 4 minutes to get to depth
>>12, then big hash will take around 2 minutes...
>You shouldn't measure time to ply, that would not give you the full benefit of
>the hash. You should use time to find the right move.
>I have never seen the hash bring only a factor of 2, even in middlegame.
>Last I tested I saw a mate in 5 being solved in 1/4 of the nodes with the hash.

Do you use killer moves?

I know that at least in version 1.17 you do not do it.

Not using killer moves can increase the advantage
of hash tables.


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